Geothermal heat pump freeze protection with electric heater staging

ABSTRACT

A method of auxiliary heat staging in a heat pump system having a geothermal water source or open loop. The method includes receiving a demand for heating in the heat pump system, receiving a temperature signal indicative of a temperature associated with a liquid in the geothermal loop, determining if the temperature associated with the liquid in the geothermal loop is lower than a first selected threshold. If the temperature is lower than the first selected threshold, then operating the heat pump system and the auxiliary heat at an increased capacity.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/837,486, filed Apr. 23, 2019, the entirecontents of which are incorporated herein by reference.

BACKGROUND

The present disclosure relates to control of a geothermal system. Moreparticularly, to a geothermal heat pump device having circulationcontrol of the ground circulating loop in a geothermal system and anauxiliary heating source staging.

Heat pumps are used in a variety of settings, for example, in HVACsystems that provide a desired air temperature in a facility. Such heatpumps commonly include a compressor, evaporator, expansion valve, andcondenser. The heat pumps input work to the refrigerant, e.g., bydriving the compressor, thereby enabling the refrigerant to extract heatfrom a source and reject it into a conditioned space, and converselyextract heat from a conditioned space and reject it into a heat sink.

In geothermal applications the “outside” heat exchanger includes aburied loop or well for closed loop and open loop systems respectively.After refrigerant expanded by the heating expansion valve, heat isexchanged with water of the well, heating the refrigerant and coolingthe water in the loop or well. In the in the geothermal well circulationcircuit, a circulating liquid such as water flows through a circulationpath, and exchanges heat with the ground ambient. In the heat pumpdevice at the contact point between the circulating water from thegeothermal well, the heat of the circulating liquid transfers thethermal energy to the circulating liquid of the refrigerant by heatexchange. Since circulating fluid or air from the building extracts heatfrom the refrigerant then circulates in the building to be heated, theinterior of the building is heated using this thermal energy.

However, in an environment where the temperature drops below thefreezing point, extended periods of low geothermal loop temperatures forexample, resulting from high heating loads, or undersized geothermalloops, the circulating liquid circulating in the source side circulationcircuit may freeze and the geothermal system may not function properly.As a countermeasure against potential freezing, it is sometimesnecessary to take measures to replace the water content of thecirculating liquid with a liquid having a lower freezing point such asan antifreeze solution. Other countermeasures include sensors and freezeprotections that monitor the temperature of the refrigerant circuitand/or loop fluid circuit and disable the geothermal loop to avoidexcessively cooling the water. Other techniques are to automaticallyheat the water in the geothermal loop using stored heat or heatingelements, or even temporarily reversing the operation of the heat pump.Yet another technique is to employ an “off” time, automatic/timedstaging of auxiliary heat, or scheduled rest time for the geothermalloop to permit the geothermal loop to recover. Another approach is tonever stage down auxiliary heat; utilizing supplemental heating toincrease heating capacity, thus allowing longer time between heat pumpstart-ups. Operating on supplemental heating, or turning it onprematurely is generally much more expensive than operation of theground source heat pump alone.

Accordingly, it is desirable to provide an uncomplicated method forensuring geothermal loop freeze protections while upstaging utilizationof supplemental heating in advance to improve efficiency under selectedconditions and/or to keep equipment in operation trouble free.

SUMMARY

According to one embodiment described herein is an A method of auxiliaryelectric heat staging in a heat pump system having a geothermal loop.The method includes receiving a demand for heating in the heat pumpsystem or building thermostat, receiving a temperature signal indicativeof a temperature associated with a liquid in the geothermal loop,determining if the temperature associated with the liquid in thegeothermal loop is lower than a first selected threshold. If thetemperature is lower than the first selected threshold, then operatingthe heat pump system and the auxiliary heat at a reduced loading or justheat pump only with no auxiliary heating based on the heat demand. Themethod also includes determining if the temperature associated with theliquid in the geothermal loop is lower than a second selected threshold.If the temperature is lower than the second selected threshold, thenoperating the heat pump system and the auxiliary electric heater at fullcapacity and then shut down the whole system when the demand issatisfied.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that the atleast one valve is a reversing valve and is included in said refrigerantcircuit for effecting operation respectively in the heating mode and ina cooling mode.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include a thermostat,the thermostat providing a signal to the controller indicative of atleast the demand for heating in the heating mode.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include a circulationfan or pump for the ambient air or fluid associated with the first heatexchanger for circulating ambient air past the first heat exchanger tofacilitate refrigerant to ambient air or hydronic fluid heat exchange.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thecontroller determines if the temperature associated with the liquid inthe geothermal loop is lower than a first selected threshold, if thetemperature is lower than the first selected threshold, then thecontroller operates the heat pump system and the auxiliary heat at anincreased capacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thecontroller determines if the temperature associated with the liquid inthe geothermal loop is lower than a second selected threshold, then thecontroller operates the heat pump system and the auxiliary electricheater at a further increased capacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thedetermining if the temperature associated with the liquid in thegeothermal loop increases above a third selected threshold, if thetemperature associated with the liquid in the geothermal loop is greaterthan the third selected threshold, then operating the heat pump systemwith the auxiliary heat at, at least the increased capacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thefirst selected threshold is selected for the temperature of the liquidin the geothermal loop at a temperature far enough away from a freezingtemperature of the liquid to permit the heat pump system to partiallyextract the geothermal heat from the geothermal loop.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thefirst selected threshold is established at a user selected temperaturebased at least in part on the fluid used. In one example 45° F. is used.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thesecond selected threshold is selected for the temperature of the liquidin the geothermal loop at temperature to avoid a freezing temperature ofthe liquid to permit the heat pump system to rest the geothermal loop.This can be done by increasing the capacity using auxiliary heating toreach the desired building temperature faster, allowing the loop torest.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thesecond selected threshold is established at a user selected temperaturebased at least in part on the fluid used. In one example a temperatureof 34° F. is used.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include thatdetermining if the temperature associated with the liquid in thegeothermal loop increases above a third selected threshold, if thetemperature associated with the liquid in the geothermal loop is greaterthan the third selected threshold, then operating the heat pump systemwith the auxiliary heat at a reduced capacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the system may include that thethird selected threshold is selected for the temperature of the liquidin the geothermal loop at temperature far enough away from a freezingtemperature of the liquid to permit the heat pump system to partiallyextract the geothermal heat from the geothermal loop.

Also disclosed herein in another embodiment is a method of auxiliaryelectric heat staging in a heat pump system having a geothermal loop.The method includes receiving a demand for heating associated with afacility in the heat pump system, receiving a temperature signalindicative of a temperature associated with a liquid in the geothermalloop, determining if the temperature associated with the liquid in thegeothermal loop is lower than a first selected threshold. If thetemperature is lower than the first selected threshold, then operatingthe heat pump system and auxiliary electric heater at an increasedcapacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include determining if the temperature associated withthe liquid in the geothermal loop is lower than a second selectedthreshold and if the temperature is lower than the second selectedthreshold, then operating the heat pump system and the auxiliaryelectric heater at a further increased capacity including full capacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the demand is generated by a thermostat inthe facility that measures the temperature of the facility anddetermines that the temperature measured is at or below a selectedthreshold.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the first selected threshold is selectedfor the temperature of the liquid in the geothermal loop at atemperature far enough away from a freezing temperature of the liquid topermit the heat pump system to partially extract heat from thegeothermal loop.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the first selected threshold isestablished at a user selected temperature based at least in part on thefluid used. In one example 45° F. is used.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the second selected threshold is selectedfor a temperature of the liquid in the geothermal loop at temperature toavoid a freezing temperature of the liquid to permit the heat pumpsystem to rest the geothermal loop.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the second selected threshold isestablished at a user selected temperature based at least in part on thefluid used. In one example 34° F. is used.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include determining if the temperature associated withthe liquid in the geothermal loop increases above a third selectedthreshold, if the temperature associated with the liquid in thegeothermal loop is greater than the third selected threshold, thenoperating the heat pump system with the auxiliary heat at the increasedcapacity.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the third selected threshold is selectedfor the temperature of the liquid in the geothermal loop at atemperature far enough away from a freezing temperature of the liquid topermit the heat pump system to partially extract heat from thegeothermal loop.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the circulation of a heat exchange fluidthrough a heat exchanger is stopped when too much heat is removed fromthe geothermal loop connected in a heat exchange relationship with theheat exchange fluid, as determined by a sensed temperature of the liquidin the geothermal loop.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the geothermal loop may be at least one ofa closed circuit loop or an open circuit well or pond.

In addition to one or more of the features described above, or as analternative, further embodiments of the method of auxiliary electricheat staging may include that the thresholds are based on whether thegeothermal loop is a closed circuit loop or an open circuit well orpond.

Additional features and advantages are realized through the techniquesof the present disclosure. Other embodiments and aspects of thedisclosure are described in detail herein and are considered a part ofthe claimed disclosure. For a better understanding of the disclosurewith the advantages and the features, refer to the description.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the disclosure, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe disclosure are apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 depicts an example of a heat pump system in accordance with anexemplary embodiment; and

FIG. 2 depicts a simplified flowchart of method of auxiliary electricheat staging in a heat pump system having a geothermal loop inaccordance with an embodiment.

DETAILED DESCRIPTION

For the purposes of promoting an understanding of the principles of thepresent disclosure, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It should nevertheless be understood that nolimitation of the scope of this disclosure is thereby intended. Thefollowing description is merely illustrative in nature and is notintended to limit the present disclosure, its application or uses. Itshould be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features. Asused herein, the term controller refers to processing circuitry that mayinclude an application specific integrated circuit (ASIC), an electroniccircuit, an electronic processor (shared, dedicated, or group) andmemory that executes one or more software or firmware programs, acombinational logic circuit, and/or other suitable interfaces andcomponents that provide the described functionality.

Additionally, the term “exemplary” is used herein to mean “serving as anexample, instance or illustration.” Any embodiment or design describedherein as “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs. The terms “at least one”and “one or more” are understood to include any integer number greaterthan or equal to one, i.e. one, two, three, four, etc. The terms “aplurality” are understood to include any integer number greater than orequal to two, i.e. two, three, four, five, etc. The term “connection”can include an indirect “connection” and/or a direct “connection”.

In general, embodiments herein relate to an application of a methodand/or system for staging auxiliary heat (commonly electric coil) in aheat pump system having a geothermal loop or water source heat pump.Demand for upstaging and activating supplemental auxiliary heating isconfigured to be independent of building load demand to ensure continualoperation of the system. Activating auxiliary electric heat earlier thandemand requests facilitates additional rest time for the geothermal loopor well by increasing the time between cycles. Upstaging shall be donewith an algorithm based on entering water temperature of medium in theclosed loop and/or facility demand.

FIG. 1 illustrates an exemplary heat pump system 100, according to anembodiment. The heat pump system 100 having an indoor portion 102positioned inside a facility 103 and an outdoor portion 104 positionedoutside the facility 103; however, in various embodiments, the heat pump100 may instead be housed in a single casing and/or disposed partiallyinside and partially outside, or either completely inside or outside thefacility 103. FIG. 1 may illustrate default or “normal” operation of theheat pump 100, with the heat pump 100 being configured to heat thefacility 103; however, it will be readily appreciated that the heat pumpsystem 100 can be reversed to cool the facility 103. It should beappreciated that while the heat pump system 100 is depicted as a splitsystem with separated indoor portions 102 and outdoor portions 104, suchdescription is merely illustrative. The heat pump system 100 could alsobe a split system of different packaging or integration, stand-alonepackaged product, or even a fully contained roof-top type ofconfiguration. In these other configurations the indoor portion and theoutdoor portion or at least parts thereof may be integrated.

The heat pump system 100 includes a compressor 106, which may belocated, for example, in the outdoor portion 104. The compressor 106includes an inlet 107 a configured to receive a lower-pressurerefrigerant and an outlet 107 b configured to discharge ahigher-pressure refrigerant. The refrigerant can be or include, withoutlimitation, Freon, R134a, propane, butane, methane, R410A, carbondioxide, nitrogen, argon, other organic or HCFC refrigerants,combinations thereof, or the like.

The compressor 106 can be any suitable single or multistage compressor,for example, a screw compressor, reciprocating compressor, centrifugalcompressor, scroll compressor axial-flow compressor, or the like. Thecompressor 106 may also be representative of multiple discrete orcooperative compressors, or be inverter driven/variable speed withmodulating output. Further, the compressor 106 may include a motor (notshown), which may be electrically powered to drive the compressor 106.In some embodiments, however, other energy sources may be employed todrive the compressor 106, such as, for example, natural gas. Thecompressor 106 may be “energized” and “de-energized,” for example, bycontrolling the power to the motor. In a single-stage embodiment of thecompressor 106, power can be provided to the motor, which in turn,supplies mechanical energy to the compressor 106, thereby “energizing”the compressor 106. Further, power can be turned off to the motor, orthe motor can be mechanically decoupled from the compressive portions ofthe compressor 106, such that the compressor 106 is “de-energized” andtherefore ceases to compress refrigerant. In multi-stage or multi-unitembodiments of the compressor 106, the compressor 106 can be“de-energized” by stopping the supply of mechanical energy to one, some,or all of the compression stages (or units) of the compressor 106.

The heat pump 100 also includes a first heat exchanger 108, which may bedisposed in the indoor portion 102, and may be fluidly coupled to thecompressor 106. The first heat exchanger 108 may be any suitable type ofheat exchanger configured to transfer heat between a refrigerant and airor another medium (e.g., water). For example, the first heat exchanger108 may include one or more coils of thermally conductive material, suchas copper, aluminum, alloys thereof, combinations thereof, or the like.In other embodiments, the first heat exchanger 108 may be oradditionally include a shell-and-tube heat exchanger, a printed circuitheat exchanger, a plate-fin heat exchanger, combinations thereof, or thelike. The air (or other medium) may be motivated past the first heatexchanger 108 via a blower 110, which may be any suitable air movingdevice, including one or more axial, radial, or centrifugal fans,blowers, pumps, compressors, combinations thereof, or the like.

The heat pump system 100 may further include at least one expansiondevice, for example, an indoor expansion device 112 positioned in theindoor portion 102, and an outdoor expansion device 114 positioned inthe outdoor portion 104. At least one of the indoor and outdoorexpansion devices 112, 114 may be fluidly coupled to the first heatexchanger 108. The expansion devices 112, 114 may each be or include oneor more types of thermal expansion valves (TEVs), Joule-Thomson valves,electronic expansion valves (EXVs) or the like. In other embodiments,one or both of the expansion devices 112, 114 may be a turbine or othertype of expander. Although not shown, the heat pump system 100 mayinclude one or more valves and/or bypass lines to enable bypass of theindoor and/or outdoor expansion devices 112, 114, for example, accordingto whether the heat pump 100 is set to cool a facility or heat afacility, as will be described in greater detail below.

The heat pump system 100 may also include a second heat exchanger 116fluidly coupled at least one of the indoor and outdoor expansion devices112, 114. In an embodiment, the second heat exchanger 116 may bedisposed about the outer extent of the outdoor portion 104 of the heatpump system 100, as schematically depicted in FIG. 1. However, in otherembodiments, the second heat exchanger 116 may be disposed in anylocation within, around, and/or proximal to the outdoor portion 104. Thesecond heat exchanger 116 may be any suitable type of heat exchangerconfigured to transfer heat between a refrigerant and air or anothermedium (e.g., water for the geothermal loop). For example, the secondheat exchanger 116 may include one or more coils of thermally conductivematerial, such as copper, aluminum, alloys thereof, combinationsthereof, or the like. In some embodiments, the second heat exchanger 116may be or additionally include a shell-and-tube heat exchanger, aprinted circuit heat exchanger, a plate-fin heat exchanger, twisted tubecoaxial, combinations thereof, or the like.

The heat pump 100 may include a pump to urge or otherwise motivate theliquid past (or through) the second heat exchanger 116. The pump 150 mayinclude a motor 120 and one or more blades or impeller (not shown), andmay be, in at least one embodiment, positioned in line with thegeothermal loop 152. The pump may be configured to the fluid into andthrough the second heat exchanger 116, returning it to the loop 152 asshown.

The heat pump system 100 may also include an accumulator 128 disposedupstream from the compressor 106. The accumulator 128 may be apressurized vessel configured to store extra refrigerant, which mayprovide refrigerant inventory control in the heat pump system 100 and/ormay store excess refrigerant. The accumulator 128 may be in line withthe compressor 106, or may be selectively branched off upstream of thecompressor inlet 107 a, for example, by a three-way valve (not shown).The heat pump 100 may further include a muffler 130 to attenuate thepropagation of noise from the compressor 106. The muffler 130 may be anysuitable noise-attenuating device. Further, one or more service valves132 may be disposed, from a fluid-flow standpoint, between thecompressor 106 and the first heat exchanger 108. The service valve 132may be or include one or more gate valves, ball valves, check valves, orany other valves which are operable to facilitate decoupling the indoorand outdoor portions 102, 104 for maintenance, repair, replacement,installation.

The heat pump 100 may also include a reversing valve 134, according toan embodiment. The reversing valve 134 may be positioned in the outdoorportion 104 and, from a fluid flow standpoint, between the compressor106 and the first heat exchanger 108 and between the second heatexchanger 116 and the compressor 106. The reversing valve 134 mayinclude two flowpaths therethrough: a first flowpath 136 and a secondflowpath 138. In one or more embodiments, the first and second flowpaths136, 138 may be discrete, preventing fluid flowing through the firstflowpath 136 from mixing with fluid flowing through the second flowpath138 and vice versa. In other embodiments, some intermixing between thefirst and second flowpaths 136, 138 may be allowed. The flowpaths 136,138 selectable to implement a cooling mode, a heating mode, or adehumidification mode for the heat pump system 100.

Further, the reversing valve 134 may have a default state and anenergized state. For example, FIG. 1 may illustrate the default state ofthe reversing valve 134. In the illustrated embodiment, when in thedefault state, the reversing valve 134 may be configured such that thefirst flowpath 136 fluidly connects the compressor outlet 107 b (e.g.,via the muffler 130) to the first heat exchanger 108 and the secondflowpath 138 fluidly connects the second heat exchanger 116 to thecompressor inlet 107 a (e.g., via the accumulator 128).

The heat pump system 100 may also include an auxiliary heater 139positioned in the indoor portion 102, proximal to the blower 110. Theauxiliary heater 139 may be an electrical resistance or inductiveheater, hydronic coil, a gas heater or furnace, a combination thereof,or the like. The auxiliary heater 139 may be configured to providesupplemental heat for the air moved into the facility 103 by the blower110 during heating mode or when the geothermal loop 152 is either notoperational (e.g., freeze condition).

The heat pump 100 may also include a controller 140 and one or moresensors such as a temperature sensor 142, which may be coupled togethersuch that the controller 140 is configured to receive a signal from thetemperature sensor 142. The temperature sensor 142 may be a thermistor,thermocouple, thermostat, infrared sensor, combinations thereof, or thelike, and may be in contact with or disposed closely proximal to thesecond heat exchanger 116 so as to gauge a temperature of the secondheat exchanger 116. The controller 140 and the temperature sensor 142may be disposed within the outdoor portion 104, or outside thereof.

The controller 140 may be or include one or more programmable logiccontrollers and may be additionally coupled with the compressor 106,reversing valve 134, fan 118, auxiliary heater 139, and any othercomponents of the heat pump 100 so as to communicate therewith. Thecontroller 140 may be configured to receive an input from thetemperature sensor 142 and provide output signals to one or more of thecompressor 106, reversing valve 134, fan 118, and auxiliary heater 139.Such output signals may control whether each component is energized orde-energized.

In operation, the controller 140 is configured to control the heat pumpsystem 100 in a manner to address and provide for a calls for heating orcooling of the facility, e.g., the building space to be conditioned. Athermostat 160 measures the temperature, humidity and the like in theconditioned space of the facility and calls for heating or coolingaccordingly.

When the heat pump system 100 is providing cooling under some conditions(extreme cold, high heating load, undersized geothermal loop, and thelike) the geothermal loop 152 can experience temperatures that may causethe liquid circulating in the loop 152 to freeze and the geothermalsystem may not function properly. As a countermeasure against potentialfreezing, sensors and freeze protection algorithms are employed thatmonitor the temperature of the geothermal loop and disable thegeothermal loop to avoid excessively cooling the water. One techniqueemployed is an “off” time or rest time for the geothermal loop 152 topermit the geothermal loop to recover to a higher temperature. However,during such a rest time or after a period of no heating, thesupplemental auxiliary heater 139 is typically activated and required tooperate at its highest stage levels to satisfy the demand for heating inthe facility 103. Commonly, this heating is achieved by not down-stagingthe auxiliary electric heat 139 and to finish/satisfy the heating callemploying the highest electric heat stage from the auxiliary electricheater 139. Alternatively, the thermostat 160 may determine that theheating demand is not being satisfied within a selected time period anddetermine that the geothermal loop is insufficient to/incapable ofsatisfying the heating demand. As a result, a rest/off time is employedto permit the geothermal loop to recover.

In an embodiment, the controller 140 or the thermostat 160 employs andexecutes a methodology to enable down-staging of the electric auxiliaryheater 139 to reduce energy consumption and/or help satisfy thetemperature demand of 103. The algorithm is based upon demand (heating)and temperature of the liquid in the geothermal loop 152. In thedescribed embodiments the temperature of the liquid (typically water andantifreeze mixture) in the geothermal loop 152 is monitor Temperaturesensor 142 monitors the entering water temperature. The temperature ofthe liquid in the geothermal loop is compared with a first selectedtemperature threshold. If the temperature of the liquid in thegeothermal loop decreases below the first selected threshold, theauxiliary electric heater is activated (if not operating) and/oroperated at an increased capacity, but not necessarily a maximumcapacity output for a selected duration. If the temperature of theliquid in the geothermal loop decreases to below a second selectedthreshold temperature (e.g., near the freeze temp), the methodologycauses the auxiliary electric heater to operates at a further increasedcapacity up to and including at full stage or power to provided heatingfor the facility 103 and satisfy the heating demand Thereby permittingthe geothermal loop an opportunity to rest and recover to an operabletemperature and state. Advantageously the electric heat up/down-stagingalgorithm of the described embodiments reduces energy consumption may bereadily automatically controlled and requires minimal user interactionand configuration. The described embodiments also aid in continualoperation of the system to help ensure temperature demand is met in thefacility.

Turning now to FIG. 2 depicting the method 200 of staging auxiliaryheating in a geothermal heat pump system 100 having a geothermal loop152. The method 200 initiates with process step 205 including receivinga demand for heating in the heat pump system 100. The demand is usuallygenerated by a thermostat 160 in the facility 103 that measures thetemperature and 160, or in combination with 160 and 140, determines thatthe measured temperature is at or below a selected threshold. At processstep 210, the method 200 continues with receiving a temperature signalindicative with a temperature associated with a liquid in the geothermalloop 152. It is then determined if the temperature associated with theliquid in the geothermal loop 152 is lower than a first selectedthreshold as depicted at process step 215. In an embodiment, the firstselected threshold is selected for a temperature of the liquid in thegeothermal loop 152 at temperature far enough away from the freezingtemperature to permit the heat pump system to partially extract heatfrom the geothermal loop 152. In one embodiment the first selectedthreshold is established at a temperature of 45° F. Though othertemperatures are possible for the first selected threshold. In anembodiment, the thresholds are configurable as a function of thegeothermal loop 152 or well design as well as the fluid employed. Aninstaller can configure the freeze limits as part of systemcommissioning as needed and the thresholds may be adjusted automaticallybased on the selected freeze limits. If the temperature exceeds (islower than) the first selected threshold, then the heat pump system 100operates the heat pump system 100 and the auxiliary heat 139 at anincreased capacity or increased or full capacity based on demand of 103in FIG. 1 as depicted at process step 220. Optionally the method 200continues at process step 225 with determining if the temperatureassociated with the liquid in the geothermal loop 152 is lower than asecond selected threshold. If the temperature is lower than the secondselected threshold, then the heat pump system operates the heat pumpsystem 100 and the auxiliary heat 139 at further increased/highercapacity including full capacity independent of the demand of 103 inFIG. 1 as depicted at process step 230. In one embodiment the secondselected threshold is established at a temperature of 34° F. Thoughother temperatures are possible for the second selected threshold asdescribed herein. In an embodiment the auxiliary heat is operated atfull capacity independent of the demand. For example, a higher thresholdmay be employed for water alone in the geothermal loop, while lowerthresholds could be employed if the geothermal loop employs variousadditive antifreeze solutions. For example, with, a 15% propylene glycolsolution the first threshold may be lowered to approximately 38° F.,while the second threshold might be reduced to 26° F. Likewise, forother antifreeze additives various thresholds may be employed asdescribed.

Continuing with the method 200, as depicted at process step 235,optionally it is determined if the measured temperature associated withthe liquid in the geothermal loop increases sufficiently to be above athird selected threshold. If it is determined if the temperatureassociated with the liquid in the geothermal loop 152 is greater thanthe third selected threshold, then the heat pump system 100 operateswith the auxiliary heat 139 in a reduced capacity as depicted atoptional process step 240. Once again, in an embodiment, the firstselected threshold is selected for a temperature of the liquid in thegeothermal loop 152 at temperature far enough away from the freezingtemperature to permit the heat pump system to extract heat from thegeothermal loop 152. Steps 235 and 240 optional, and such are shown inFIG. 2 as a dashed.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more features, integers, steps, operations, element components,and/or groups thereof. For the purposes of this disclosure, it isfurther understood that the terms “inboard” and “outboard” can be usedinterchangeably, unless context dictates otherwise.

While the present disclosure has been described in detail in connectionwith only a limited number of embodiments, it should be readilyunderstood that the present disclosure is not limited to such disclosedembodiments. Rather, the present disclosure can be modified toincorporate any number of variations, alterations, substitutions,combinations, sub-combinations, or equivalent arrangements notheretofore described, but which are commensurate with the scope of thepresent disclosure. Additionally, while various embodiments of thepresent disclosure have been described, it is to be understood thataspects of the present disclosure may include only some of the describedembodiments.

What is claimed is:
 1. A heat pump system having a geothermal groundsource loop with auxiliary heat staging, the heat pump systemcomprising: a geothermal loop circulating a liquid in the geothermalloop in a first heat exchange relationship with geothermal heat; arefrigerant circuit for circulating refrigerant having a plurality offlowpaths in the heat pump system; a first heat exchanger being at leastdisposed in the refrigerant circuit for circulating the refrigerant, andat least disposed in a path of ambient air or fluid of a facility, therefrigerant in a second heat exchange relationship with the ambient airor fluid; a second heat exchanger being disposed in the refrigerantcircuit for circulating the refrigerant, and disposed in fluidcommunication with the geothermal loop, the refrigerant in a third heatexchange relationship with the liquid in the geothermal loop; at leastone compressor connected into the refrigerant circuit for compressingthe refrigerant from its inlet pressure to its discharge pressure underconditions of operation of the refrigerant circuit; at least oneexpansion device connected at the inlet of a heat exchanger in which therefrigerant is being vaporized; at least one valve disposed in therefrigerant circuit and operably selecting one or more flow paths of theplurality of flowpaths of the refrigerant circuit including the firstheat exchanger, second heat and direction of flow of the refrigeranttherethrough for selecting a particular mode of operation of the heatpump system; an auxiliary heater disposed in the ambient air of thefacility and operable to add heat to the ambient air under selectedconditions; a temperature sensor a disposed at the geothermal loop, thetemperature sensor operable to provide a temperature signal indicativeof a temperature associated with the liquid in the geothermal loop; anda controller operable to receive the temperature signal from thetemperature sensor and control activation of the auxiliary heaterresponsive to a demand for heating in at least a heating mode and aunder selected conditions associated with the geothermal loop.
 2. Theheat pump system of claim 1, wherein the at least one valve is areversing valve and is included in said refrigerant circuit foreffecting operation respectively in at least one of the heating mode acooling mode and a dehumidification mode.
 3. The heat pump system ofclaim 1, further including a thermostat, the thermostat providing asignal to the controller indicative of at least the demand for heatingin the heating mode.
 4. The heat pump system of claim 1, furtherincluding a circulation fan or a pump for the ambient air or fluidassociated with the first heat exchanger for circulating ambient air orfluid past the first heat exchanger to facilitate refrigerant to ambientair or fluid heat exchange.
 5. The heat pump system of claim 1, whereinthe controller determines if the temperature associated with the liquidin the geothermal loop is lower than a first selected threshold, if thetemperature is lower than the first selected threshold, then thecontroller operates the heat pump system and the auxiliary heat at anincreased capacity.
 6. The heat pump system of claim 5, wherein thecontroller determines if the temperature associated with the liquid inthe geothermal loop is lower than a second selected threshold, then thecontroller operates the heat pump system and the auxiliary heater at, ata further increased capacity.
 7. The heat pump system of claim 5,further including determining if the temperature associated with theliquid in the geothermal loop increases above a third selectedthreshold, if the temperature associated with the liquid in thegeothermal loop is greater than the third selected threshold, thenoperating the heat pump system with the auxiliary heat at, at least theincreased capacity.
 8. The heat pump system of claim 5, wherein thefirst selected threshold is selected for the temperature of the liquidin the geothermal loop at a temperature far enough away from a freezingtemperature of the liquid to permit the heat pump system to partiallyextract the geothermal heat from the geothermal loop.
 9. The heat pumpsystem of claim 8, wherein the first selected threshold is establishedat a temperature based at least in part on the liquid in the geothermalloop and a particular application.
 10. The heat pump system of claim 6,wherein the second selected threshold is selected for the temperature ofthe liquid in the geothermal loop at temperature to avoid a freezingtemperature, nor nearing a freezing temperature, of the liquid to permitthe heat pump system to rest the geothermal loop.
 11. The heat pumpsystem of claim 10, wherein the second selected threshold is establishedat a temperature of based at least in part on the liquid in thegeothermal loop and a particular application.
 12. The heat pump systemof claim 7, wherein the third selected threshold is selected for thetemperature of the liquid in the geothermal loop at temperature farenough away from a freezing temperature of the liquid to permit the heatpump system to extract the geothermal heat from the geothermal loop. 13.A method of auxiliary heat staging in a heat pump system having ageothermal loop, the method comprising: receiving a demand for heatingassociated with a facility in the heat pump system; receiving atemperature signal indicative of a temperature associated with a liquidin the geothermal ground source or water well loop; determining if thetemperature associated with the liquid in the geothermal loop is lowerthan a first selected threshold; and if the temperature is lower thanthe first selected threshold, then operating the heat pump system anauxiliary heater at, at least, an increased or higher capacity based onthe demand.
 14. The method of auxiliary heat staging in a heat pumpsystem of claim 13, wherein the demand is generated by a thermostat inthe facility that measures the temperature of the facility anddetermines that the temperature measured is at or below a selectedthreshold.
 15. The method of auxiliary heat staging in a heat pumpsystem of claim 13, wherein the first selected threshold is selected forthe temperature of the liquid in the geothermal loop at a temperaturefar enough away from a freezing temperature of the liquid to permit theheat pump system to extract heat from the geothermal loop.
 16. Themethod of auxiliary heat staging in a heat pump system of claim 15,wherein the first selected threshold is established at a temperaturebased at least in part on the liquid in the geothermal loop and aparticular application.
 17. The method of auxiliary heat staging in aheat pump system of claim 13, further including determining if thetemperature associated with the liquid in the geothermal loop is lowerthan a second selected threshold; and if the temperature is lower thanthe second selected threshold, then operating the heat pump system andthe auxiliary electric heater at, at least, at a further higher capacitythan the increased capacity.
 18. The method of auxiliary heat staging ina heat pump system of claim 17, wherein the second selected threshold isselected for a temperature of the liquid in the geothermal loop attemperature to avoid a freezing temperature of the liquid to permit theheat pump system to rest the geothermal loop.
 19. The method ofauxiliary heat staging in a heat pump system of claim 16, wherein thesecond selected threshold is established at a temperature based at leastin part on the liquid in the geothermal loop and a particularapplication.
 20. The method of auxiliary heat staging in a heat pumpsystem of claim 13, further including determining if the temperatureassociated with the liquid in the geothermal loop increases above athird selected threshold, if the temperature associated with the liquidin the geothermal loop is greater than the third selected threshold,then operating the heat pump system with the auxiliary heat at theincreased capacity.